This paper takes as its starting point a multidimensional analysis of interviews with both native speakers of English and upper-intermediate to advanced EFL learners (Pérez-Paredes and Sánchez-Tornel, 2015a). The native data were taken from The Louvain Corpus of Native English Conversations (LOCNEC) and the British component of the Contrastive Analysis of Orality in Spoken English Corpus (CAOS-E Corpus 2, Aguado et al. 2012); the learner data were taken from the Louvain International Database of Spoken English Interlanguage (LINDSEI, Gilquin et al. 2010). The interviews used in the analysis all follow the same set pattern and are made up of three main tasks: a personal narrative based on a set topic (an experience that taught them a lesson, a country that impressed them, or a film or play they liked/disliked), a free discussion mainly about university life, hobbies, foreign travel or plans for the future and a picture description. In Pérez-Paredes and Sánchez-Tornel (2015a; 2015b) both the native and the learner data were tagged for part of speech at the University of Northern Arizona (using a modified CLAWS tagset) and scores (Biber 1988) were subsequently computed for each interview and for each task for the following five dimensions of linguistic variation identified in Biber (1988): Dimension 1: involved versus information production, Dimension 2: narrative versus non-narrative concerns, Dimension 3: explicit versus situation-dependent reference, Dimension 4: overt expression of persuasion, Dimension 5: abstract versus non-abstract information. The multidimensional analysis revealed that the learners tend to score higher on the dimensions under scrutiny than the native speakers performing the same tasks. The analysis also shed light on variations in dimension scores between the various learner populations investigated and between the three interview parts. This research methodology has been used by Hardy and Römer (2013) to show variation in successful student writing in different disciplines represented in the MICUSP corpus (Römer & O'Donnell 2011). This paper is intended as a follow-up to Pérez-Paredes and Sánchez-Tornel (2015a) as it seeks to explore why the learners in the LINDSEI corpus scored higher than the native speakers in the same communicative situation, in particular, on Dimension 1. Our main research question is what makes the learner interviews more involved, interactional and affective than the native interviews? Pérez-Paredes and Sánchez-Tornel (2015a) found that the LINDSEI-ES informants understood the picture description as someway oriented towards expressing their opinions. Our study concentrates on two learner populations: the French and Spanish LINDSEI data sets. Both positive and negative features associated with Dimension 1 (Biber 1988, Conrad 2001) are scrutinized in the POS tagged learner and the native data. Positive features include, for example, reduced lexical content markers like demonstrative and indefinite pronouns and affective aspect of personal involvement markers like private verbs and possibility modals. Negative features include nouns, prepositions, attributive adjectives and the type/token ratio. Our analysis reveals a rather complex picture. It is not because one variety scores higher than another on Dimension 1 that all the positive features typically associated with this dimension systematically occur with higher frequencies in this variety. There is also considerable variation within each corpus. Having said this, on the whole, the learners under study tend to use a series of positive features more frequently than the native speakers. These include, among others, first and second person pronouns, indefinite pronouns, clausal coordination, causative adverbials and wh-questions. The learners can also be seen to use positive features such as contractions and hedges less frequently than the native speakers, which may point to performance as well as pragmatic concerns not so present in non-native communication (Aguado et al. 2012). The paper aims to paint an 'involvement profile' of the learner and the native speaker interviewees and considers the possible impact of some of the interview(er) variables (e.g. status of the interviewer). Our qualitative study also sets out to investigate differences between the two learner varieties (e.g. what makes the interviews with the Spanish learners even more involved than the French learner interviews?) and between the three tasks in the interviews (e.g. is the picture description less involved than the personal narrative and free discussion?). The paper concludes by evaluating the use of multidimensional analysis when exploring interviews with native speakers and EFL learners. References Aguado, P. Pérez-Paredes, P. & Sánchez, P. 2012. Exploring the Use of Multidimensional Analysis of Learner Language to promote Register Awareness. System, 40,1: 90-103. Biber, D. 1988. Variation across Speech and Writing. Cambridge: Cambridge University Press. Conrad, S. 2001. Variation among disciplinary texts: A comparison of textbooks and journal articles in biology and history. In Multi-dimensional studies of register variation in English. S. Conrad & D. Biber (eds.), 94-107. Harlow, England: Pearson Education. Gilquin, G., De Cock, S., & Granger, S. 2010. The Louvain International Database of Spoken English Interlanguage. Handbook and CD-ROM. Louvain-la-Neuve: Presses Universitaires de Louvain. Hardy, J. & Römer, U. 2013. Revealing disciplinary variation in student writing: a multi-dimensional analysis of the Michigan Corpus of Upper-level Student Papers (MICUSP). Corpora, 8,2: 183-2017. Pérez-Paredes, P. & Sánchez-Tornel, M. 2015a. A multidimensional analysis of learner language during story reconstruction in oral proficiency interviews. In Callies, M. & Götz, S. (eds) Learner Corpora and their application in language testing and assessment. Amsterdam: John Benjamins. In press. Pérez-Paredes, P. & Sánchez-Tornel, M. 2015b. Understanding the role of speaking tasks in oral proficiency interviews (OPI): a Multidimensional Analysis of native speaker language. Forthcoming. Römer, U. & O'Donnell, M. B. 2011. From student hard drive to web corpus (part 1): The design, compilation and genre classification of the Michigan Corpus of Upper-level Student Papers (MICUSP). Corpora, 6,2: 159-177.